The present invention relates to the production of aralkyl tertiary hydroperoxides and more particularly to the production of p-diisopropylbenzene dihydroperoxide.
In the production of aralkyl tertiary polyhydroperoxides such as, for example, p-diisopropylbenzene dihydroperoxide, there is also produced the corresponding monohydroperoxide. Indeed, the rate of formation of the monohydroperoxide is approximately proportional to the concentration of the aryl tertiary alkane in the reaction mixture and that of the dihydroperoxide to the concentration of the monohydroperoxide. The reaction comes to a virtual standstill before all of the monohydroperoxide is converted to the dihydroperoxide and consequently for a given amount of the aryl tertiary alkane only a small proportion of the dihydroperoxide is obtained.
It is known that the oxidation reaction can be conducted so as to yield a considerably higher amount of the aralkyl tertiary dihydroperoxide if the dihydroperoxide is separated from the oxidation reaction mixture alternately or concurrently with the oxidation reaction while the oxidation is continued with the remaining reaction mixture. As a practical matter, in a continuous process the dihydroperoxide is continuously removed from the reaction mixture and the remaining portion of the oxidation reaction product is recycled to the oxidation reaction to convert the large amounts of monohydroperoxide present in the recycle stream to dihydroperoxide.
Unfortunately, the oxidation reaction product from which the dihydroperoxide has been removed and which is recycled to the oxidation reaction, in addition to containing large amounts of the monohydroperoxide and unreacted aryl tertiary alkane, also contains undesirable by-products and impurities which are quite detrimental to the efficiency of the oxidation reaction. For example, it is known that in such reactions poly-oxy-functional reaction by-products such as aralkyl tertiary dialkanols, keto aryl tertiary alkanols, etc. are also produced. As a consequence of the above-described recycle to the oxidation reactor, the poly-oxy-functional by-products continue to build up to the point where, if the oxidation reaction is to be conducted efficiently and economically, it may become necessary to completely discharge the reactor contents and charge the reactor with fresh reactants. Such a solution is both expensive and time consuming.
One method of avoiding by-product build-up in the reactor recycle loop is to purge from the system a portion of the recycle stream. Thus a fraction of the recycle stream can be evaporatively stripped to produce a light fraction containing the unreacted aryl tertiary alkane and monohydroperoxide for recycle and a heavy fraction containing the poly-oxy-functional by-products and which can be sent to waste. While such a process will control the by-product build-up such that the oxidation reaction can be conducted in a continuous manner, it results in a loss of the precursor monohydroperoxide since some of the latter remains in the heavy fraction. Thus, a process which would effectively remove deleterious amounts of the poly-oxy-functional byproducts from the reaction loop without a concomitant loss of significant amounts of monohydroperoxide is highly desirable.